In order to maintain the expected level of losses, marine insurance law and practice developed a range of rules to control the insured’s behaviour during the period when the underwriter is on risk. This chapter is concerned with those rules that restrict the insured’s ability to bring about losses by deliberate or reckless conduct. Allegations of criminal and/or fraudulent conduct by the insured have serious consequences. If proven, there are likely to be long-term implications for the individuals concerned and their business interests. The Marine Insurance Act 1906, by way of section 55(2)(a), establishes that losses proximately caused by wilful misconduct are not recoverable. In The Brilliante Virtuoso, Teare J. found that the owner of the vessel had conspired with the master, the chief engineer and the co-ordinator of the salvage operation to permit armed men to enter the vessel in an apparent piratical attack by armed men masquerading as security guards.